By CT scanning PAHMA 5-513, an unwrapped mummy group composed of an adult Nile crocodile with juvenile crocodiles massed on its back, we learned more about how the adult and baby crocodiles lived, died and were mummified.

We hoped that imaging the interior of the mummy group would reveal if the adult had been eviscerated (had its entrails removed) as part of the mummification process, how the crocodiles died, the gender of the large crocodile, and other surprises. Like wrapped crocodile mummy PAHMA 6-20100, 5-513 underwent two sets of scans at Stanford University. First we scanned the mummy with a clinical CT scanner to identify features of potential interest, and then followed up with high resolution scans using the C-arm scanner in the lab of Dr. Rebecca Fahrig, Department of Radiology, Stanford University

No signs of blunt force trauma were visible on the cranium, vertebrae and other bones, ruling out some modes of death. The CT scans also revealed intact organs, indicating that the adult crocodile had not been eviscerated. One of the organs visible in the CT renderings is a full stomach. The crocodile’s stomach contains the bones of small prey, round radiopaque objects that appear to be rocks, and a manmade object…

Initially, the concentration of round dense objects in the stomach was slightly puzzling. However, it turns out that crocodilians actually consume stones that remain in their stomachs. The stones help to crush and grind food, which crocodiles do not chew. Acidic stomach fluids also break down the food chemically. Biologists believe that the ingestion of stones may have a secondary function as well, providing additional weight that aids the crocodile in floating just below the surface of the water.

Many small animal bones are mixed in with the rocks.

Fish skeletons in the stomach of PAHMA 5-513. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using an Axiom Artis dTA with DynaCT, Siemens Healthcare. Created using High Definition Volume Rendering® software by Fovia, Inc.

Claw (?) bones of an unidentified animal in the stomach of PAHMA 5-513. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using an Axiom Artis dTA with DynaCT, Siemens Healthcare. Created using High Definition Volume Rendering® software by Fovia, Inc.

The high resolution scans performed at Dr. Fahrig’s lab revealed a final surprise in the crocodile’s stomach. Amidst all the bones and the rocks, there is a metal hook.

Stomach contents of PAHMA 5-513, with radiopaque metal hook (shown in yellow) and round objects that appear to be rocks. Images acquired by Dr. Rebecca Fahrig, Department of Radiology, Stanford University, using an Axiom Artis dTA with DynaCT, Siemens Healthcare. Created using High Definition Volume Rendering® software by Fovia, Inc.

The J-shaped hook, with a barbed tip and eyelet, resembles fish hooks from Greco-Roman Egypt. The compact surface and lack of voluminous corrosion products suggest that the hook may be made of a copper alloy rather than of iron.

How did the hook end up in the crocodile’s stomach? Based on its location inside of the stomach and proximity to fish skeletons, the hook may have been lodged in a fish consumed by the crocodile shortly before its death.

The hook may also have been deposited inside of the crocodile during mummification. At the 2011 AIC conservation conference, a conservator from the Field Museum shared CT images of a Ptolemaic period gazelle mummy. There is a very similar metal hook in the gazelle’s hindquarters, suggesting that such hooks were used by embalmers in the course of animal mummy preparation.

5th century BC Greek writer Herodotus offers yet another possible scenario. His Histories includes a section on Egyptian customs, including crocodile worship and mummification, and techniques for capturing and dispatching the dangerous beasts. Herodotus claims that the Egyptians had numerous ways of catching crocodiles, and details one method that involves luring a crocodile out of the water with bait on a hook:

They bait a hook with a chine of pork and let it float out into midstream, and at the same time, standing on the bank, beat a live pig to make it squeal. The crocodile makes a rush towards the squealing pig, encounters the bait, gulps it down, and is hauled out of the water. The first thing the huntsman does when he has got the beast on land is to plaster its eyes with mud; this done, it is dispatched easily enough-but without this precaution it will give a lot of trouble.

(trans. de Sélincourt, 1954)

Of course we can’t know exactly how the hook ended up in the stomach of the mummified crocodile, but it’s fun to imagine a Herodotean turn of events!

Many thanks to Dr. Rebecca Fahrig (Stanford University), eHuman Inc., and Shay Kilby of Fovia, Inc. for their assistance with scanning the mummy and rendering images!